What is a 2N2907 Transistor : Pin Configuration & Its Working

In Electronics, a PNP bipolar junction transistor called 2n2907 transistor is designed for switching applications and low power amplifying purposes. It can operate at moderate temperatures and high speeds. It comes in a metal can package type with high current, low voltage, and power values. This article gives a brief description of the 2N2907 transistor pin configuration, specifications, and how to use it in various applications.

What is a 2N2907 Transistor?

A PNP Bipolar Junction Transistor (BJT) manufactured in the metal can package with a high current of 600mA and low voltage of 40V for low power amplifying purposes and switching applications is called the 2n2907 transistor. It is a three-terminal device, which has an emitter, base, and collector. It has a DC current gain of 100-300, which represents its amplification capacity because it is used for switching and amplification applications.

This is a bipolar PNP transistor because the electrons and holes are responsible for carrying out the conduction current in the circuit. But holes are the majority charge carriers in this transistor.

It is made up of semiconductor material. As this is a PNP transistor, the N-type layer is present in between the two P-type materials. The N-side represents the base terminal and its polarity is negative. While the P-side represents the emitter terminal and its polarity is positive.

It is also referred to as a current-controlled device because the minimum current at the base terminal controls the maximum current at the emitter and collector terminals.

In the conducting state of the transistor, the polarity of the base terminal is negative regarding the emitter terminal. The collector to base junction gets reverse biased. So, that the polarity of the collector terminal is negative to the base terminal.

Since, the NPN and PNP transistors working similarly, except that the polarities of the voltage and direction of the current are reverse in the PNP transistor when compared to the NPN transistor.

2N2907 Pin Configuration

The 2n2907 transistor is a 3-pin Or 3-terminal device. It contains Emitter, Base, and Collector as terminals or leads or pins. The 2n2907 pin configuration/pin description is explained below. The basic 2n2907 PNP transistor with pin configuration is shown below.

Pin 1 (Emitter): The current of the transistor drains out through this pin.

Pin 2 (Base): The biasing of the transistor is controlled through the base terminal.

Pin 3 (Collector): Through this terminal, the current flows into the transistor.

• For amplification, the base current should have the potential to control high current at the collector and the emitter terminals.
• The collector terminal is lightly doped and the emitter terminal is heavily doped.
• The emitter and collector terminals differ from each other due to their doping levels and size.

2N2907 Transistor Specifications/Features

The 2n2907 transistor specifications or features are as follows

• It is available in TO-92 and TO-18 package types
• It is a lead (Pb) free device
• It has a high current value with a maximum of 60 mA
• The voltage value is low – maximum 40 V
• The collector to emitter voltage VCEO of transistor – maximum 40 V
• The emitter to base voltage VEBO of transistor – 5 V (Normal)
• The collector to base voltage VCBO of  transistor – maximum 60 V
• The collector current is a maximum – 600mA
• At ambient temperature, the power dissipation of the transistor is about 400mW
• The DC current gain (hfe) is high – 100 to 300 (maximum)
• The operation and storage temperature is between -65° to +150°C.

Circuit Diagram/How To Use?

The circuit diagram of the 2n2907 transistor and its equivalent circuit symbol is shown in the figure below.

The total emitter current of the transistor is the mix of base current and collector current. This is a type of PNP transistor and is manufactured in the TO-92 package type with different pin configurations.

In the 2n2907 PNP transistor, the internal transfer of holes allows the current to flow through the external circuit. While in NPN transistors, the external flow of electrons carries out the conduction current from emitter to collector terminals.

When the base terminal is connected to GND (Ground), or no supply is given to the base, then the 2n2907 transistor goes into forwarding bias condition. When the signal or supply is given to the base terminal, then the transistor goes into reverse biased condition.

The 2n2907 transistor gets fully biased and allows a 500mA of maximum current through the collectors terminal with a collector to emitter voltage (VCE) of a maximum of 1.6 Volts. This condition of the transistor represents the saturation region. When the transistor’s base current is removed, it goes into the OFF state, which shows the cut-off region.

Where to Use/Applications

A few 2N2907 transistor applications are given below.

• This type of transistor is used in lower power amplification circuits
• It is used in several applications of switching circuits
• It is used in manufacturing dual LEDs, siren, or lamp flashers.
• It is used in analog and linear amplification.

However, most of us will have a question that how to use and where to use this 2n2907 transistor. Here is an answer to this. The major applications of 2n2907 transistors include switching applications and low power amplifying circuit applications.

2N2907 Transistor acts as a Switch

When this PNP transistor is used as a switch, then it operates in saturation and cut-off regions. This transistor is in ON condition by default. But it is not in the ON state completely until the base terminal is not connected to GND. If the base terminal of the 2n2907 PNP transistor is connected to GND (ground), then it gets reverse biased and it is said to be in an ON state.

If the supply is given to the base terminal, then it stops the flow of conducting current between the emitter and collector terminals and it is said to be in an OFF state. Resistance is added and connected in series with the transistor for protection. To determine the value of the added resistance, the following formula is used,

R_B = V_BE / I_B

Where V_BE = Base to Emitter voltage = 5V (normally)

I_B = Base current

R_B = Base resistance

The 2n2907 transistor provides 200mA of maximum base current. From this, we can determine the value of resistance added in series with the transistor.

2N2907 Transistor acts as an Amplifier

When this transistor is used as an amplifier, it operates in an active region. When the base terminal of the 2n2907 PNP transistor is connected to the GND pin, then the maximum current of 600mA is allowed to pass through the collector to the emitter terminal. In this way, the current is amplified by this transistor.

In an amplifier circuit, the 3 transistor configurations can be used, such as common base, common collector, and common emitter If the low power amplifying is required in a circuit, then this transistor is used. It is also used to amplify the current and power of the circuit. We can determine the amplification factor in terms of power. The formula to calculate the current gain is,

Gain (hfe) = I_C / I_B

Where I_B represents base current and

I_C represents the collector current of the given circuit.

Alternative 2N2907 Transistor

The 2n2222A NPN transistor is the alternative 2n2907 transistor. It is a bipolar NPN transistor, which allows the high current of 800mA across the emitter and collector terminals. It is mainly used in switching applications, controlling the speed of the motors, Rectifier and Inverter circuits, and Darlington pair.

It is available in package type of TO-92. It is mainly used in switching loads of high currents. The equivalent transistors of 2n2222A are 2n2904 PNP transistor, 2n2907 PNP transistor, 2n3907 PNP transistor, BC637, BC148, S9014, 2n4403, MPS2222, KN2222, PN2222, and KTN2222.

Thus, this is all about an overview of the 2n2907 transistor datasheet which includes definition, pin configuration, circuit diagram, where to use, specifications and applications. The equivalent transistors of 2n2907 PNP transistors are MPS2907, 2n2907a, NTE159M, PN2907, KTN2907, and KN2907 transistors. Here is a question for you, “What are the technical specifications of the 2n2222A transistor? “